How do you calibrate the iPad battery?

How do you calibrate the iPad battery and is it necessary to discharge battery 100%. I have the 3 rd generation iPad, it has been almost a year since I purchased it and the battery when fully charged reads 100%. Recently, I visited my local Jump Plus store and the staff said I should drain the batteries on my iPad & iPhone completely until they are dead and recharge once a month. Is this accurate? It is my understanding that you should not drain the batteries completely? Also, is that the same as calibrating the battery?